Many American Indian (AI) women never receive services for serious mental health problems resulting from traumatic events, violence exposure and maltreatment. AI women suffer higher lifetime rates of Post-traumatic Stress Disorder (PTSD) (20-23%), that often co-occur with excessive drinking and risky sexual behaviors. These factors magnify risk for human immunodeficiency virus and sexually transmitted disease (HIV/STI). In full development with tribal partners, this application, in response to R34 PA-09-146: Pilot and Feasibility Studies in Preparation for Drug Abuse Prevention Trials proposes a 3-year project to culturally adapt and pilot an empirically supported trauma-focused treatment, Cognitive Processing Therapy (CPT) for PTSD, substance use and HIV/STI sexual risk behavior among 50 AI women. Additionally, we will assess the feasibility, acceptability and treatment fidelity of delivering CPT via AI community health workers in a resource-limited tribal reservation. This project is innovative in both its focus and its methods. It brings a culturally responsive intervention to an understudied and highly vulnerable population. It will culturally adapt and modify an evidence-based CPT intervention to address health risk behaviors (substance and alcohol use and disorder and high risk sexual behavior). Its significance lies in its potential to advance science in the area of PTSD, substance use treatment and HIV/STI prevention among AI women. Study data would benefit tribal and rural communities and the mental health field. Finally, it is geared toward developing the research infrastructure and mental health treatment capacity serving AI women living in rural settings, a group at risk for an expanding HIV/AIDS epidemic. If successful, findings from this pilot will provide evidence for a larger effectiveness trial. The AIMS are AIM I. Adapt the evidence-based CPT intervention in full collaboration with tribal partners. This will be done in accordance with the CDC's Map of Adaptation Process and involves formative research with tribal leaders, potential consumers, providers, and health care administrators using qualitative methodology. AIM 2. Assess this intervention delivered by Native American community health workers for feasibility and acceptability in a resource-limited rural reservation setting. AIM 3. Conduct a two-group, single-site waitlist randomized controlled pilot trial of a 12-session, 3-month CPT intervention among 50 sexually active and substance using AI women with PTSD or sub-threshold PTSD. Determine preliminary efficacy and estimate an effect size in terms of three primary outcomes: (a) PTSD symptomatology; (b) substance use; (c) high risk sexual behavior. PUBLIC HEALTH RELEVANCE: The results of this study have the potential to advance science in the area of PTSD and substance disorder treatment and HIV/STI prevention among American Indian women. Additionally, it could tell us whether such an intervention might have the potential to reduce HIV risk behaviors and, ultimately, the spread of HIV, in this very vulnerable group.